QuakeIndex

quarry blast · reviewed by a seismologist

M 1.8md

6km E of Atascadero, CA

· -0.3 km deep · released about 13 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Luis Obispo County 17 kmKings County 97 kmMonterey County 106 kmSanta Barbara County 117 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
Magnitude
M 1.8 (md)
Depth
-0.3 km below the surface
Felt
no reports yet
Nearest
San Luis Obispo County, 17 km SE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2117 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

USGS catalogues this as quarry blast, not an earthquake.

How big was it?

This earthquake released about 13 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 810,000× the energy of this one
  3. Around the size people start to feel M 3.0 72× the energy of this one
  4. This earthquake M 1.8 about 13 lb of TNT

Energy from the Gutenberg–Richter relation (log10E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.

Where

Epicentre 35.4800, -120.6043. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
San Luis Obispo County, CA 17 km (11 mi) NW of here earthquakes near San Luis Obispo County
Kings County, CA 97 km (60 mi) SW of here earthquakes near Kings County
Monterey County, CA 106 km (66 mi) SE of here earthquakes near Monterey County
Santa Barbara County, CA 117 km (73 mi) NNW of here earthquakes near Santa Barbara County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

48 earthquakes have been recorded within 50 km since this one.

  1. 1.7 9km WSW of Atascadero, CA
  2. 2.2 4km WSW of Paso Robles, CA
  3. 1.5 11km NNE of Cambria, CA
  4. 2.2 4km ESE of Cholame, CA
  5. 1.6 7km E of Atascadero, CA
  6. 1.7 8km SW of Atascadero, CA
  7. 1.6 6km NNW of Cholame, CA
  8. 3.2 4km NNW of Cholame, CA
  9. 1.6 11km WSW of Templeton, CA
  10. 2.3 5km SSE of Parkfield, CA
  11. 2.3 13km NNE of Cambria, CA
  12. 2.3 11km WSW of Morro Bay, CA
  13. 1.7 11km WSW of Templeton, CA
  14. 1.5 7km NNW of Cholame, CA
  15. 1.5 6km NNE of Santa Margarita, CA

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

For this area

The largest earthquake within 50 km in our catalogue was M 4.3 on 2019-12-17 — it released about 6,200 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.